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#include <stdint.h>
#include <cairo/cairo.h>
#include "cairo.h"
#ifdef WITH_GDK_PIXBUF
#include <gdk-pixbuf/gdk-pixbuf.h>
#endif
void cairo_set_source_u32(cairo_t *cairo, uint32_t color) {
cairo_set_source_rgba(cairo,
(color >> (3*8) & 0xFF) / 255.0,
(color >> (2*8) & 0xFF) / 255.0,
(color >> (1*8) & 0xFF) / 255.0,
(color >> (0*8) & 0xFF) / 255.0);
}
cairo_surface_t *cairo_image_surface_scale(cairo_surface_t *image,
int width, int height) {
int image_width = cairo_image_surface_get_width(image);
int image_height = cairo_image_surface_get_height(image);
cairo_surface_t *new =
cairo_image_surface_create(CAIRO_FORMAT_ARGB32, width, height);
cairo_t *cairo = cairo_create(new);
cairo_scale(cairo, (double)width / image_width,
(double)height / image_height);
cairo_set_source_surface(cairo, image, 0, 0);
cairo_paint(cairo);
cairo_destroy(cairo);
return new;
}
#ifdef WITH_GDK_PIXBUF
cairo_surface_t* gdk_cairo_image_surface_create_from_pixbuf(const GdkPixbuf *gdkbuf) {
int chan = gdk_pixbuf_get_n_channels(gdkbuf);
if (chan < 3) {
return NULL;
}
const guint8* gdkpix = gdk_pixbuf_read_pixels(gdkbuf);
if (!gdkpix) {
return NULL;
}
gint w = gdk_pixbuf_get_width(gdkbuf);
gint h = gdk_pixbuf_get_height(gdkbuf);
int stride = gdk_pixbuf_get_rowstride(gdkbuf);
cairo_format_t fmt = (chan == 3) ? CAIRO_FORMAT_RGB24 : CAIRO_FORMAT_ARGB32;
cairo_surface_t * cs = cairo_image_surface_create (fmt, w, h);
cairo_surface_flush (cs);
if ( !cs || cairo_surface_status(cs) != CAIRO_STATUS_SUCCESS) {
return NULL;
}
int cstride = cairo_image_surface_get_stride(cs);
unsigned char * cpix = cairo_image_surface_get_data(cs);
if (chan == 3) {
int i;
for (i = h; i; --i) {
const guint8 *gp = gdkpix;
unsigned char *cp = cpix;
const guint8* end = gp + 3*w;
while (gp < end) {
#if G_BYTE_ORDER == G_LITTLE_ENDIAN
cp[0] = gp[2];
cp[1] = gp[1];
cp[2] = gp[0];
#else
cp[1] = gp[0];
cp[2] = gp[1];
cp[3] = gp[2];
#endif
gp += 3;
cp += 4;
}
gdkpix += stride;
cpix += cstride;
}
} else {
/* premul-color = alpha/255 * color/255 * 255 = (alpha*color)/255
* (z/255) = z/256 * 256/255 = z/256 (1 + 1/255)
* = z/256 + (z/256)/255 = (z + z/255)/256
* # recurse once
* = (z + (z + z/255)/256)/256
* = (z + z/256 + z/256/255) / 256
* # only use 16bit uint operations, loose some precision,
* # result is floored.
* -> (z + z>>8)>>8
* # add 0x80/255 = 0.5 to convert floor to round
* => (z+0x80 + (z+0x80)>>8 ) >> 8
* ------
* tested as equal to lround(z/255.0) for uint z in [0..0xfe02]
*/
#define PREMUL_ALPHA(x,a,b,z) \
G_STMT_START { z = a * b + 0x80; x = (z + (z >> 8)) >> 8; } \
G_STMT_END
int i;
for (i = h; i; --i) {
const guint8 *gp = gdkpix;
unsigned char *cp = cpix;
const guint8* end = gp + 4*w;
guint z1, z2, z3;
while (gp < end) {
#if G_BYTE_ORDER == G_LITTLE_ENDIAN
PREMUL_ALPHA(cp[0], gp[2], gp[3], z1);
PREMUL_ALPHA(cp[1], gp[1], gp[3], z2);
PREMUL_ALPHA(cp[2], gp[0], gp[3], z3);
cp[3] = gp[3];
#else
PREMUL_ALPHA(cp[1], gp[0], gp[3], z1);
PREMUL_ALPHA(cp[2], gp[1], gp[3], z2);
PREMUL_ALPHA(cp[3], gp[2], gp[3], z3);
cp[0] = gp[3];
#endif
gp += 4;
cp += 4;
}
gdkpix += stride;
cpix += cstride;
}
#undef PREMUL_ALPHA
}
cairo_surface_mark_dirty(cs);
return cs;
}
#endif //WITH_GDK_PIXBUF
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